Operating Segments - Active Partner Companies by Segment (Detail)	Dec. 31, 2019	Dec. 31, 2018
Aktana, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	17.80%	18.90%
Clutch [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	41.20%	41.20%
Flashtalking, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	10.10%	10.10%
InfoBionic [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	25.20%	25.40%
Lumesis, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	43.50%	43.70%
Media Math Inc [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	13.30%	13.40%
meQuilibrium [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	32.70%	33.10%
Moxe Health [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	29.90%	32.40%
Prognos [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	28.70%	28.70%
QuanticMind, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	24.20%	24.20%
Sonobi [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	21.60%	21.60%
Syapse, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	20.00%	20.00%
T-REX Group, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	13.70%	21.10%
Trice [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	16.60%	17.40%
WebLinc [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	38.50%	38.50%
Zipnosis [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	37.70%	34.70%